Water-based metal working oil agent

ABSTRACT

A water-based metalworking fluid contains a component (A) of alkanolamine represented by a formula (1) below as an amine component and a component (B) of alkanolamine represented by a formula (2) below as an amine component, a molar ratio of an amine component having a molecular weight of 90 or less to a total of the amine components (the amine component having a molecular weight of 90 or less/the total of the amine components) is 0.67 or less. 
     
       
         
         
             
             
         
       
     
     In the formula, R 1  represents hydrogen or an alkyl group having 1 to 3 carbon atoms; n is 1 to 3; and R 1  may be mutually the same or different. 
     
       
         
         
             
             
         
       
     
     In the formula: R 2  represents an alkyl group having 1 to 10 carbon atoms; and Z 1  and Z 2  each independently represent an alkylene group having 2 to 8 carbon atoms.

TECHNICAL FIELD

The present invention relates to a water-based metalworking fluid usedin metalworking such as cutting or grinding.

BACKGROUND ART

A metalworking fluid used in metalworking is categorized into anoil-type (oil-based) fluid and a water-type (water-based) fluid, thelatter of which is more frequently used because such a water-based fluidis excellent in cooling capabilities and infiltration capabilities andfree from a risk of causing a fire. Such a water-based metalworkingfluid, which is to be diluted with water in use, is required to haverust resistance. As such a rust resistant component, it is generallyknown to use alkanolamine such as monoethanolamine, diethanolamine andtriethanolamine (see Patent Literature 1).

CITATION LIST Patent Literature(s)

Patent Literature 1: JP-A-11-209774

SUMMARY OF THE INVENTION Problem(s) to be Solved by the Invention

The water-based metalworking fluid generally exhibits more favorablerust resistance at a larger content of a rust resistant component.However, when an amine-based rust resistant component (e.g.,alkanolamine) is contained, odor is derived from amines to occasionallyhave an adverse influence on human bodies and working environments.Accordingly, a type and a content of the rust resistant component stillneed to be studied.

An object of the present invention is to provide a water-basedmetalworking fluid that exhibits an excellent rust resistance and causesless odor to be more environmentally friendly and less harmful to humanbodies.

Means for Solving the Problem(s)

In order to solve the above problems, the invention provides awater-based metalworking fluid as follows.

(1) According to an aspect of the invention, a water-based metalworkingfluid contains a component (A) of alkanolamine represented by a formula(1) below as an amine component and a component (B) of alkanolaminerepresented by a formula (2) below as an amine component, a molar ratioof an amine component having a molecular weight of 90 or less to a totalof the amine components (the amine component having a molecular weightof 90 or less/the total of the amine components) is 0.67 or less.

In the formula, R′ represents hydrogen or an alkyl group having 1 to 3carbon atoms; n is 1 to 3; and R′ may be mutually the same or different.

In the formula: R² represents an alkyl group having 1 to 10 carbonatoms; and Z¹ and Z² each independently represent an alkylene grouphaving 2 to 8 carbon atoms.

(2) In the water-based metalworking fluid in the above aspect of theinvention, n in the formula (1) representing the component (A) ofalkanolamine is 2 or 3.(3) In the water-based metalworking fluid in the above aspect of theinvention, the component (A) of alkanolamine comprises1-amino-2-propanol.(4) In the water-based metalworking fluid in the above aspect of theinvention, one or both of Z¹ and Z² in the formula (2) representing thecomponent (B) of alkanolamine are an alkylene group(s) having 2 carbonatoms.(5) In the water-based metalworking fluid in the above aspect of theinvention, the component (B) of alkanolamine comprisesN-methyldiethanolamine and cyclohexyldiethanolamine.(6) The water-based metalworking fluid in the above aspect of theinvention further contains an aliphatic carboxylic acid.(7) A water-based metalworking fluid according to another aspect of theinvention is prepared by diluting the water-based metalworking fluidaccording to the above aspect of the invention with water, an amount ofthe water being 200 or less times as much as an amount of thewater-based metalworking fluid according to the above aspect of theinvention by a mass ratio.

According to the above aspect of the invention, since alkanolaminehaving a specific structure is contained as the amine component and themolar ratio of the amine component having a molecular weight of 90 orless is defined as being equal to or less than a specific ratio, thewater-based metalworking fluid that exhibits an excellent rustresistance and causes less odor to be more environmentally friendly andless harmful to human bodies can be provided.

DESCRIPTION OF EMBODIMENT(S)

Exemplary embodiment(s) of the invention will be described below.

In an exemplary embodiment, a water-based metalworking fluid contains acomponent (A) of alkanolamine represented by a formula (1) below and acomponent (B) of alkanolamine represented by a formula (2) as aminecomponents, a molar ratio of an amine component having a molecularweight of 90 or less to a total of amine components (i.e., an aminecomponent having a molecular weight of 90 or less/a total of aminecomponents) is 0.67 or less.

First of all, the component (A) will be described. The component (A) isused for particularly providing rust resistance to the water-basedmetalworking fluid. In the above formula (1), R¹ represents hydrogen oran alkyl group having 1 to 3 carbon atoms. n is 1 to 3. R¹ may bemutually the same or different. When n is 4 or more, solubility of thecomponent (A) is unfavorably reduced. n is more preferably 2 or 3, mostpreferably 2. In addition, when any one of R′ has 4 or more carbonatoms, the solubility of the component (A) and rust resistance for ironare unfavorably deteriorated.

An amine compound having a molecular weight of 90 or less is preferablyincluded in the component (A) of alkanolamine in order to improve rustresistance.

Examples of the component (A) are 1-amino-2-propanol,2-amino-2-methyl-1-propanol, 1-amino-2-butanol, 2-amino-1-propanol, and3-amino-2-butanol. Among the above, in view of the rust resistance foriron, 1-amino-2-propanol and 2-amino-2-methyl-1-propanol are preferable.

In the exemplary embodiment, the component (A) may be provided by asingle one or a plurality of the above substances.

Next, alkanolamine as the component (B) will be described. The component(B) contributes to improving rust resistance and reducing odor.

In the formula (2), which represents the component (B), R² represents analkyl group having 1 to 10 carbon atoms. When R² has a non-cyclicstructure, R² preferably has 1 to 4 carbon atoms, more preferably 1carbon atom. When R² has 11 or more carbon atoms, solubility and rustresistance of the component (B) are unfavorably deteriorated. Z¹ and Z²each independently represent an alkylene group having 2 to 8 carbonatoms. One or both of Z′ and Z² are preferably an alkylene group having2 carbon atoms. When at least one of Z′ and Z² has 1 carbon atom, thecomponent (B) is degraded to generate formaldehyde, which isenvironmentally unfavorable. When at least one of Z′ and Z² has 9 ormore carbon atoms, the solubility of the component (B) is unfavorablydeteriorated.

Examples of the component (B) are N-methyldiethanolamine,N-ethyldiethanolamine, cyclohexyldiethanolamine,N-n-propyldiethanolamine, N-i-propyldiethanolamine,N-n-butyldiethanolamine, N-i-butyldiethanolamine, andN-t-butyldiethanolamine. Among the above, it is particularly preferableto use N-methyldiethanolamine and cyclohexyldiethanolamine incombination.

In the exemplary embodiment, the component (B) may be provided by asingle one or a plurality of the above substances.

When contents of the amine components used as the rust resistantcomponent in the water-based metalworking fluid are the same, the aminecomponent having a smaller molecular weight exhibits more favorable rustresistance. This means that the amine component having a smallermolecular weight can provide rust resistance equivalent to those of theamine component having a larger molecular weight with a content lowerthan a content of the amine component having a larger molecular weight.However, the amine component having a smaller molecular weight,particularly a molecular weight of 90 or less, is highly volatile, sothat the amine component intensifies odor as the content thereof isincreased in the fluid. Accordingly, it is generally difficult toachieve both of less odor and rust resistance by only adjusting thecontent of the rust resistant component.

In the water-based metalworking fluid in the exemplary embodiment, themolar ratio of the amine component having a molecular weight of 90 orless to the total of the amine components (i.e., the amine componenthaving a molecular weight of 90 or less/the total of the aminecomponents) is 0.67 or less, preferably in a range of 0.6 to 0.4, morepreferably in a range of 0.55 to 0.5. When the molar ratio exceeds 0.67,odor of the water-based metalworking fluid is unfavorably intensified tohave an adverse influence on human bodies and working environments.

In view of handling ability, the water-based metalworking fluid in theexemplary embodiment is preferably prepared as a stock solution having ahigh concentration, so that a user dilutes the stock solution asnecessary with water to use the diluted stock solution as metalworkingfluid.

A solvent for the stock solution is the most preferably water, but maybe mineral oil or synthetic oil.

Such mineral oil or synthetic oil used as the solvent for preparing thestock solution is not specifically limited but may be any base oilgenerally used for the metalworking fluid. Such mineral oil or syntheticoil preferably has kinematic viscosity at 40 degrees C. in a range of 1to 50 mm²/s, more preferably in a range of 2 to 30 mm²/s. When thekinematic viscosity of the base oil is too high, the fluid may adhere toa workpiece, whereby a large amount of the fluid may be carried togetherwith the workpiece, which may be economically unfavorable. In contrast,when the kinematic viscosity of the base oil is too low, mist generationmay unfavorably deteriorate workability. A pour point (i.e., the indexof low-temperature fluidity) of the base oil is not subject to anylimitations, but preferably −10 degrees C. or less.

As the mineral oil or the synthetic oil, various kinds of oil areavailable. The mineral oil or the synthetic oil may be suitably selectedtherefrom, depending on the usage.

Examples of the mineral oil are oil fraction obtained by atmosphericallydistilling paraffin-based crude oil, intermediate-based crude oil ornaphthene-based crude oil or by vacuum-distilling residual oil formed byatmospheric distilling, and purified oil obtained by refining the oilfraction in accordance with an ordinary method. Examples of the purifiedoil are solvent-refined oil, hydrogenerated refined oil,dewaxing-processed oil, and white clay-processed oil.

On the other hand, examples of the synthetic oil are poly-α-olefin,α-olefin copolymer, polybutene, alkylbenzene, polyolester, diacid ester,polyoxyalkylene glycol, polyoxyalkylene glycol ester, polyoxyalkyleneglycol ether, and silicone oil. Among the above synthetic oil,poly-α-olefin and α-olefin copolymer are preferable. The base oil maycontain single one or a plurality of the above mineral oil or syntheticoil, or may contain both the mineral oil and the synthetic oil.

The component (A) is preferably contained in the stock solution at aratio of 1 to 20 mass % of the total amount of the stock solution, morepreferably 5 to 14 mass %, further preferably 9 to 13 mass %. When theratio of the component (A) exceeds 20 mass %, odor is unfavorablyintensified.

The component (B) is preferably contained in the stock solution at aratio of 5 to 30 mass % of the total amount of the stock solution, morepreferably 10 to 30 mass %, further preferably 22 to 29 mass %. When theratio of the component (B) is less than 5 mass %, odor is unfavorablyintensified. Even when the ratio of the component (B) exceeds 30 mass %,rust resistance for iron is not further enhanced, resulting in highcost, which is economically unfavorable.

When the water-based metalworking fluid in the exemplary embodiment isused, the above-described stock solution is preferably diluted withwater an amount of which is 200 times or less as much as that of thestock solution by mass ratio. The stock solution is more preferablydiluted to 10 to 100 times, further preferably 20 to 50 times. When thestock solution is diluted with water the amount of which exceeds 200times as much as that of the stock solution, the prepared fluidunfavorably exhibits insufficient rust resistance.

The water-based metalworking fluid may be blended as necessary withvarious known additives as long as an object of the present invention isnot hampered. Examples of the additives are a fungicide, aliphaticcarboxylic acid, metal deactivator (anticorrosion agent), extremepressure agent, oiliness agent, surfactant and antifoaming agent.

The fungicide is exemplified by 2-pyridylthio-1-oxide salt. Examples ofthe fungicide are 2-pyridylthio-1-oxide sodium, zincbis(2-pyridylthio-1-oxide), and bis(2-sulfidepyridine-1-olato) copper.Among the above, 2-pyridylthio-1-oxide sodium is particularly preferablebecause the substance is effective on general bacteria and molds in awide range even when contained therein with a low concentration. In viewof blending effects, the fungicide is contained in the stock solutionwith a content of approximately 0.01 to 5 mass % of the total amount ofthe final diluted fluid.

The aliphatic carboxylic acid is added to the fluid in order to furtherenhance cutting capabilities, grinding capabilities and rust resistanceof the fluid. The aliphatic carboxylic acid is exemplified by carboxylicacid having 6 to 60 carbon atoms and/or dicarboxylic acid. Specificexamples of the aliphatic carboxylic acid are caproic acid, caprylicacid, nonane acid, lauric acid, stearic acid, olein acid, ricinoleinacid, hydroxyfatty acid (such as recinoleic acid or 12-hydroxystearicacid), arachidic acid, behenic acid, melissic acid, isononane acid(3,5,5-trimethylhexane acid), neo-decane acid, isostearic acid, fattyacid extracted from fat and oil such as soy oil fatty acid, coconut oilfatty acid or rape-seed oil fatty acid, acid extracted from petroleumsuch as naphthene acid, adipic acid, sebacic acid (decanedioic acid),dodecanoic diacid, monohydroxy arachidic acid or dihydroxy arachidicacid, and synthetic fatty acid such as dimer or trimer of olein acid,recinoleic acid, ricinolein acid, 12-hydroxystearic acid. In view ofantifoaming of the fluid and stability of hard water, particularlypreferable examples of monocarboxylic acid are caproic acid having 8 to10 carbon atoms, nonane acid having 8 to 10 carbon atoms, decane acidhaving 8 to 10 carbon atoms, isononane acid having 8 to 10 carbon atoms,and neodecane acid having 8 to 10 carbon atoms while examples ofparticularly preferable dicarboxylic acid are nonane diacid, undecanoicdiacid, sebacic acid (decanedioic acid), and dodecanoic diacid. In viewof blending effects, the aliphatic carboxylic acid is contained in thestock solution with a content of approximately 0.1 to 1.5 mass % of thetotal amount of the final diluted fluid.

The aliphatic carboxylic acid reacts with the amine components to forman aliphatic carboxylic acid amine salt, thereby enhancingprocessability or emulsion stability serving as an emulsifier to furtherenhance rust resistance.

A sum of the aliphatic carboxylic acid component and the aminecomponents preferably accounts for 40 to 60 mass % of the total amountof the stock solution, more preferably 47 to 55 mass %, furtherpreferably 50 to 53 mass %.

Examples of the metal deactivator are benzotriazole, benzotriazolederivative, imidazoline, pyrimidine derivative, thiadiazole andthiadiazole. The metal deactivator may be provided by a single one or aplurality of the above substances. In view of blending effects, themetal deactivator is contained in the stock solution with a content ofapproximately 0.01 to 3 mass % of the total amount of the final dilutedfluid.

Examples of the extreme pressure agent are a sulfur-based extremepressure agent, a phosphorus-based extreme pressure agent, an extremepressure agent containing sulfur and metal and an extreme pressure agentcontaining phosphorus and metal. The extreme pressure agent may beprovided by a single one or a plurality of the above substances. Theextreme pressure agent may be any extreme pressure agent, as long as theextreme pressure agent contains sulfur atoms and/or phosphorus atoms inits molecule and as long as the extreme pressure agent can provide loadbearing effects and wear resistance. Examples of the extreme pressureagent containing sulfur in its molecule are sulfurized fat and oil,sulfurized fatty acid, ester sulfide, olefin sulfide, dihydrocarbylpolysulfide, a thiadiazole compound, an alkylthiocarbamoyl compound, atriazine compound, a thioterpene compound, a dialkylthiodipropionatecompound and the like. In view of blending effects, the extreme pressureagent is contained in the stock solution with a content of approximately0.05 to 0.5 mass % of the total amount of the final diluted fluid.

Examples of the oiliness agent are a fatty acid compound such as fattyalcohol, fatty acid or fatty acid metal salt, an ester compound such aspolyol ester, sorbitan ester or glyceride, an amine compound such asfatty amine and the like. In view of blending effects, the oilinessagent is contained in the stock solution with a content of approximately0.2 to 2 mass % of the total amount of the final diluted fluid.

Examples of the antifoaming agent are methyl silicone oil,fluorosilicone oil, and polyacrylate. In view of blending effects, theantifoaming agent is contained in the stock solution with a content ofapproximately 0.004 to 0.02 mass % of the total amount of the finaldiluted fluid.

The surfactant is not subject to any limitations. A nonionic surfactant,an anionic surfactant, a cationic surfactant, an ampholytic surfactantor a mixture thereof is usable as the surfactant. Preferable examples ofthe surfactant are a nonionic surfactant, an anionic surfactant, or amixture thereof.

Examples of the nonionic surfactant include a polyoxyalkylene surfactantsuch as: polyoxyalkyleneglycol, a monoether compound thereof or adiether compound thereof; and glycerin, an adduct of glycerin withalkylene oxide or an ether compound of glycerin, esters of carboxylicacid and alcohol, and an adduct of alkylamine with alkylene oxide.

Examples of the anionic surfactant include a salt of carboxylic acid(e.g., a saturated or unsaturated fatty acid or hydroxy fatty acidhaving 7 to 22 carbon atoms) or sulfonic acid with amine or metal, anester of a polycondensation product of a hydroxy fatty acid (e.g.,ricinoleic acid) with fatty acid or a salt of the ester with amine ormetal, phosphoric ester salts such as sulfates (e.g., dialkyl sodiumsulfosuccinate), a polymerized polymer surfactant provided by partiallysaponifying olefin (e.g., styrene) with a maleic anhydride copolymerizedproduct, and a naphthalenesulfonate-formalin fused polymer surfactant.

The water-based metalworking fluid in the exemplary embodiment, which isdiluted as necessary with water so that its concentration is adjustedsuitably for the usage, is preferably applied in various metalworkingfields such as cutting, grinding, polishing, squeezing, drawing,flatting and the like. Further, because of an excellent rust resistancefor metal products and less odor, the water-based metalworking fluid inthe exemplary embodiment is less harmful to environments and humanbodies.

EXAMPLES

Next, the invention will be described in more detail with reference toExamples. However, the invention is not limited at all by the Examples.

Examples 1 to 4, Comparatives 1 to 3

A water-based metalworking fluid (stock solution) according to each ofExamples 1 to 4 and Comparatives 1 to 3 was prepared by blendingcomponents shown in Table 1. After the prepared stock solution wasdiluted with water to a certain concentration, Examples 1 to 4 andComparatives 1 to 3 each were evaluated in terms of the followingcharacteristics. Evaluation results are shown in Table 1.

(1) Rust Resistance (in Accordance with DIN51360-02-A)

Test for rust resistance was conducted at room temperature for two hourson diluted solutions prepared by diluting the stock solution with tapwater to the concentration of 1.0 mass %, 1.1 mass %, 1.2 mass %, 1.3mass %, 1.4 mass %, 1.5 mass % and 2.0 mass % respectively. The minimumconcentration at which a rust value had become 0 was set as limitconcentration (mass %) in terms of rust resistance.

(2) Odor

An aqueous solution was prepared by diluting the stock solution with anion-exchange water so that the concentration of the stock solution was10.0 mass %. 100 mL of the aqueous solution was hermetically sealed in a300 mL conical flask and heated at 100 degrees C. for three minutes. Theheated aqueous solution was measured in terms of odor intensity using anodor sensor (e-nose mobile manufactured by Karumoa Inc.) A valueindicates an odor index (relative value) representing an odor intensity.The larger value indicates the intenser odor.

TABLE 1 Compar- Compar- Comparative Example 1 Example 2 Example 3Example 4 ative 1 ative 2 3 Blending Decanedioic acid 2.9 2.9 2.9 2.9 —2.9 2.9 Composition Dodecanedioic acid 2.2 2.2 2.2 2.2 12.3 2.2 2.2(mass %) Neodecanoic acid 9.9 9.9 9.9 9.9 — 9.9 9.9 3,5,5-trimethylhexanoic acid — — — — 1.0 — — N-methyldiethanolamine (Component B) 16.822.1 13.3 9.8 — — — 1-amino-2-propanol (Component A) 12.2 9.2 14.3 16.324.6 22.0 24.5 cyclohexyldiethanolamine (Component B) 6.2 6.2 6.2 6.210.0 6.2 0.0 1,2,3-benzotriazole 0.5 0.5 0.5 0.5 1.0 0.5 0.5 Othercomponents¹⁾ 0.9 0.9 0.9 0.9 0.9 0.9 0.9 Water 48.4 46.1 49.8 51.3 50.255.4 59.1 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Aminecomponent having a molecular weight of 0.50 0.37 0.58 0.67 0.86 0.901.00 90 or less/Total amine components (mol/mol) Total of Component A(mass %) 12.2 9.2 14.3 16.3 24.6 22.0 24.5 Total of Component B (mass %)23.0 28.3 19.5 16.0 10.0 6.2 0.0 Acid component + Amine component 50.752.9 49.2 47.8 48.9 43.7 39.9 Evaluation Limit concentration of rustresistance (mass %) 1.1 1.1 1.1 1.1 1.1 1.2 1.3 Item Odor (Intensity)3365 3225 3805 3924 4310 4417 4781

As is obvious from Table 1, the water-based metalworking fluid in eachof Examples 1 to 4 exhibits an excellent rust resistance and causes lessodor. In contrast, since the water-based metalworking fluid in each ofComparatives 1 to 3 does not contain the essential components requiredin the invention, the odor intensity is high although the rustresistance is excellent.

INDUSTRIAL APPLICABILITY

A water-based metalworking fluid of the invention is usable in ametalworking field such as cutting or grinding.

1. A water-based metalworking fluid comprising: a component (A) ofalkanolamine represented by formula (1) below as a first aminecomponent; and a component (B) of alkanolamine represented by formula(2) below as a second amine component, wherein the water-basedmetalworking fluid has a molar ratio of an amine component having amolecular weight of 90 or less to a total of amine components of 0.67 orless.

where each R¹ represents hydrogen or an alkyl group having 1 to 3 carbonatoms; n is 1, 2 or 3; and the R¹'s are mutually the same or different,

where R² represents an alkyl group having 1 to 10 carbon atoms; and Z¹and Z² each independently represent an alkylene group having 2 to 8carbon atoms.
 2. The water-based metalworking fluid according to claim1, wherein n is 2 or
 3. 3. The water-based metalworking fluid accordingto claim 1, wherein the component (A) comprises 1-amino-2-propanol. 4.The water-based metalworking fluid according to claim 1, wherein one orboth of Z¹ and Z² are each an alkylene group having 2 carbon atoms. 5.The water-based metalworking fluid according to claim 1, wherein thecomponent (B) comprises N-methyldiethanolamine andcyclohexyldiethanolamine.
 6. The water-based metalworking fluidaccording to claim 1, further comprising an aliphatic carboxylic acid.7. The water-based metalworking fluid according to claim 1, beingdiluted with water, wherein the water has an amount that is 200 or lesstimes of the amount of the water-based metalworking fluid by mass.